A tandem type image forming apparatus as an electro-photographic type image forming apparatus is known in which are provided a plurality of photosensitive drums, a transfer belt positioned in confrontation therewith, a plurality of process cartridges for a plurality of colors such as for example, yellow, magenta, cyan and black, and a drawer unit configured to support the process cartridges.
Japanese patent application publication No. 2010-102285 discloses such a tandem type image forming apparatus in which each process cartridge is provided with a drum cleaning unit configured to remove waste toner remaining on each photosensitive drum associated with each process cartridge, and a waste toner container configured to accumulate the waste toner removed by the drum cleaning unit.